1. Field of the Invention
The present invention relates generally to vehicle cooling systems, and more particularly to control of a cooling system fan motor during a motor lock state.
2. Description of the Related Art
Conventionally, in an automotive cooling system, a fan is operated to cool refrigerant flowing through a system heat exchanger. The current flowing to the fan motor (hereinafter motor input current) is monitored, and the motor, and thus the fan, are stopped when an overcurrent level is detected.
The above-mentioned motor overcurrent may be caused when the cooling fan freezes and locks, as well as when the cooling fan locks due to debris, gravel, or other foreign matter.
System drive requests for the cooling fan are broadly divided into engine cooling requests and air-conditioner refrigerant cooling requests. In the above-described apparatus, when the motor input current is at an overcurrent level when the motor is frozen and locked during an air-conditioner refrigerant cooling fan-drive request, the electric motor is stopped. Consequently, the electric motor cannot be driven again even if temperature within the engine compartment rises and an engine cooling fan-drive request is generated unless the motor is re-started from a completely stopped state.